A method of this kind is known, for example from U.S. Pat. No. 4,511,207. However, this document does not disclose how the assembly formed can be separated into individual directional couplers. It has been found in practice that it is very difficult to separate the couplers, having small dimensions and being situated very near to one another, without inflicting damage. True mass production of optical components where large numbers of components are simultaneously manufactured at comparatively low costs, therefore, is not very well feasible. An object of the invention is to improve the method so that a comparatively large number (for example, tens) of components can be simultaneously formed and simply separated.